School of Materials, University of Manchester, MSS Tower, Manchester, M13 9PL, UK.
Nanoscale. 2018 Oct 21;10(39):18565-18575. doi: 10.1039/c8nr07440b. Epub 2018 Sep 27.
The localised surface plasmon resonance (LSPR) of Au nanoparticles (NPs) as well as its interaction with nearby entities provides a wealth of fundamental and practical information at the nanometre scale. A number of studies have investigated core-shell NPs with Au cores and polymer shells that are temperature-responsive. However, there are very few studies of pH-responsive Au-polymer NP shells. Precipitation polymerisation is a scalable method and here we establish such a method to synthesise pH-responsive Au-poly(methyl methacrylate) copolymer core-shell NPs without the need for pre-functionalisation. The comonomers used were methacrylic acid (MAA) or 2-carboxyethyl acrylate (CEA) and the shells were crosslinked with ethylene glycol dimethacrylate. A series of five core-shell systems with collapsed shell thicknesses less than 30 nm are studied. The shell-thicknesses for the CEA-based core-shell NPs are relatively thin (≤5 nm) compared to related Au-polymer core-shell NPs prepared using precipitation polymerisation. The LSPR properties of the core-shell NPs were dependent on the shell thickness and were successfully simulated using finite difference time domain (FDTD) calculations. Two systems are considered further as exemplars. The MAA-based core-shell system with the thickest shell exhibited enhanced colloidal stability to added electrolyte. The CEA-based core-shell dispersion with the thinnest shells displayed reversible pH-triggered aggregation and was cytocompatible for HeLa cells. Proof-of-concept data are presented that demonstrate intracellular pH reporting.
金纳米粒子（NPs）的局域表面等离子体共振（LSPR）及其与附近实体的相互作用，在纳米尺度上提供了丰富的基础和实用信息。许多研究都研究了具有金核和聚合物壳的核壳 NPs，这些 NPs 对温度有响应。然而，对 pH 响应的 Au-聚合物 NP 壳的研究非常少。沉淀聚合是一种可扩展的方法，在这里我们建立了一种不需要预官能化的方法来合成 pH 响应的 Au-聚（甲基丙烯酸甲酯）共聚物核壳 NPs。所用的共聚单体为甲基丙烯酸（MAA）或 2-羧乙基丙烯酸酯（CEA），壳层用乙二醇二甲基丙烯酸酯交联。研究了五个具有小于 30nm 塌陷壳厚度的核壳系统。与使用沉淀聚合制备的相关 Au-聚合物核壳 NPs 相比，基于 CEA 的核壳 NPs 的壳厚度相对较薄（≤5nm）。核壳 NPs 的 LSPR 性质取决于壳厚度，并成功地使用有限差分时域（FDTD）计算进行了模拟。进一步考虑了两个系统作为范例。具有最厚壳的基于 MAA 的核壳系统表现出增强的胶体稳定性，对添加的电解质具有增强的胶体稳定性。具有最薄壳的基于 CEA 的核壳分散体显示出可逆的 pH 触发聚集，并且对 HeLa 细胞具有细胞相容性。提出了证明概念的数据，证明了细胞内 pH 报告。
